Embodiments of the present invention pertain to radio-frequency (RF) amplifiers, and in particular, to wide band and ultra wide band (UWB) amplifiers for on-chip receivers.
A low noise figure in receivers helps to accurately detect signals. This is especially true for single receivers that may be used to receive signals within a wide or an ultra wide frequency band. Ultra wide band refers to a frequency band used as a wireless communication channel, which may range, for example, from 3 GHz to 10 GHz. To achieve a low noise figure, low-noise amplification of the received signals may be performed from an antenna input. Conventional wide band amplifiers have used resistive feedback to help achieve wide band response and improve amplifier stability. One problem with the use of resistive feedback is that noise levels may become unsuitable for use in many receivers, especially wide band and receivers. Another problem with the use of resistive feedback is that resistive feedback may result in input impedance values that are unsuitable for wide band receiver front ends. Reactive feedback has also been used to overcome some of the problems with resistive feedback, however the use of reactive feedback is generally not suitable for wide band applications. This is particularly true in the case of ultra wide band amplification where the higher frequencies to be amplified may be around the limits of frequency response of the transistors used in the design. Thus there is a general need for an improved ultra wide band amplifier. There is also a need for an ultra wide band amplifier with improved noise performance. There is also a need for an improved receiver.